Conventionally, in a working station where an operator coexists with an apparatus such as a robot, the apparatus has been surrounded by a safety fence so that the operator may not enter into the safety fence while the apparatus is in operation. However, because the safety fence is fixed, and it largely surrounds a movable range of the apparatus, a working station area including a working area of the operator naturally grows larger, which has incurred an increase of a floor space of a work place.
In JP-B2-3419313, there is disclosed a safety system in place of the safety fence, for the purpose of making effective use of the working station area.
FIG. 12 is a view for explaining the safety system in JP-B2-3419313, in which robots 101 move along a running path 102 to perform work on facilities 103. A detection range A1 is set around each of the robots 101, and when an operator M gets in touch with this detection range A1, movement of the robot 101 is stopped.
Because the detection range A1 moves together with the robot 101, it is possible to use the working station area more effectively, as compared with the fixed safety fence. The detection range A1 had better be as large as possible, from a viewpoint of safety of the operator M. However, as the detection range A1 is made larger, the working station area grows larger inevitably, and a moving distance of the robot 101 is increased, which incurs deterioration of productivity.
In view of the above, such technique that safety of an operator can be secured without increasing a working station area, when productivity is improved, has been required.